As expected, Apple has released an update to Airport Utility (desktop and IOS) that now supports IPv6 configuration - version 6.1 desktop, IOS vesion 1.1.
And they have added a new entry field called 'IPv6 Delegated Prefix" in the Tunnel configuration (and maybe elsewhere)
I'm guessing I enter my "2001::xxxx....:/64" in its entirety there.
If whatever address you listed is your routed /64, then yes
I don't have a value set in mine for IPv6 Delegated Prefix on my tunnel terminating Airport. If I had to guess, I'd think that field would be for one learned from DHCP-PD and more of an informational field than an input field. Alas, no real documentation on what that one's for as of yet.